How does Atlas handle Nim package updates?

Atlas manages Nim package updates by directly invoking `nimble update` or `nimble update --all` through its `bash` tool. It captures the full output of these commands, ensuring that all information regarding the update process, including any warnings or initial errors, is available for analysis and subsequent fixing.

Can Atlas fix compile-time macros in Nim after an upgrade?

Yes, Atlas can address issues related to compile-time macros in Nim. By analyzing the Nim compiler's error output from `nimble build`, Atlas identifies problems within macro expansions or their usage. It then uses its `edit` tool to modify the macro definitions or their call sites, ensuring they are compatible with the upgraded dependency's API.

How does Atlas ensure Nim code style after fixes?

Atlas ensures Nim code style consistency by automatically running `nph`, Nim's official formatter, on any modules it has modified. This step is typically performed after all compilation and test failures have been resolved, guaranteeing that the codebase adheres to established formatting standards before changes are committed.

What safety features does Atlas offer for Nim code changes?

Atlas provides several safety features for Nim code changes, including permission-gated tool calls, a read-only plan agent for drafting changes, and presenting a unified diff for every proposed edit. All changes require explicit developer approval before being written to disk or committed to Git, giving you full control over your Nim project.

Does Atlas integrate with Nim's `std/unittest` module?

Yes, Atlas fully integrates with Nim's `std/unittest` module. It uses `nimble test` via `bash` to execute your project's unit tests. If tests fail, Atlas analyzes the output to identify regressions and uses its `edit` tool to fix the relevant Nim source or test files until all tests pass, ensuring the integrity of your codebase.

Can Atlas read my Nim project's `.nimble` file?

Yes, Atlas is designed to read your Nim project's `.nimble` file. It understands the package structure, required dependencies, and other configurations defined within it. This allows Atlas to accurately manage dependencies and understand the context of your Nim project when performing upgrades and fixes.

How does Atlas know what changed in an upgraded Nim library?

Atlas can use its `webfetch` tool to retrieve the release notes or changelog of an upgraded Nim library directly from the web. This provides Atlas with concrete information about breaking changes, new features, and deprecations, allowing it to make informed decisions when fixing compile and test failures in your Nim codebase.

Upgrade a dependency and fix the breakage in Nim with Atlas in 2026

Upgrading a Nim dependency and resolving subsequent breakage is a streamlined process with Atlas, the terminal-native AI coding agent. Atlas directly interacts with your Nim toolchain, including `nimble` for package management, `nimble test` for running tests, and `nph` for formatting, ensuring fixes are applied correctly and idiomatically within your codebase.

How Atlas upgrades Nim dependencies and captures output

Atlas initiates dependency upgrades in Nim projects by executing `nimble update --all` through its `bash` tool, capturing the complete output. This ensures that even large outputs, potentially exceeding 100 lines, are saved to a file for thorough review, providing a precise record of the upgrade process and any initial warnings or errors.

When you instruct Atlas to upgrade a dependency in your Nim project, it leverages its `bash` tool to run `nimble update --all`. This command updates all dependencies listed in your `.nimble` file to their latest compatible versions. Atlas is designed to capture the entire output from this `nimble` operation. If the output is extensive, exceeding typical terminal buffer limits, Atlas automatically saves it to a file. This allows you to use the `read` tool to inspect the full details of the upgrade, including any deprecation warnings or initial compilation issues reported by `nimble` itself, before any code modifications begin. This approach ensures that Atlas works with the real Nim toolchain, not an abstraction, providing accurate context for subsequent fixes.

How Atlas uses Nim compiler output to fix breakage

After upgrading, Atlas uses its `bash` tool to run `nimble build`, meticulously analyzing the Nim compiler's error messages to identify breakage. This direct interaction with the compiler output, rather than guessing, allows Atlas to pinpoint specific issues, such as a breaking change in a library like `version 2.0` of a common utility, and then use its `edit` tool to apply precise fixes.

Once dependencies are updated, Atlas doesn't assume what broke. Instead, it uses its `bash` tool to execute `nimble build`, allowing the Nim compiler to enumerate all compile-time errors. Atlas then parses this real compiler output, understanding the exact nature and location of each error. For instance, if a function signature changed in an upgraded library, the Nim compiler will report a type mismatch or an unknown identifier. Atlas uses its `edit` tool to navigate to the problematic call site in your Nim source files, such as `src/my_module.nim`. It can then leverage the `lsp` tool's `goToDefinition` operation to inspect the new signatures directly within the upgraded package's source code, ensuring that the applied fixes, whether it's adjusting parameters or renaming a procedure, align perfectly with the new API. This iterative process of `nimble build` and `edit` continues until the project compiles cleanly.

How Atlas addresses Nim test failures and formatting

Atlas ensures a robust Nim codebase by running `nimble test` through `bash` to catch runtime regressions, and then automatically formats touched modules with `nph`. This two-step verification and standardization process, often involving 3-5 iterations of fixing and re-testing, guarantees that all changes not only compile but also pass existing unit tests defined using `std/unittest` and adhere to Nim's formatting conventions.

Beyond compilation, Atlas is configured to address test failures. After achieving a clean build, Atlas uses its `bash` tool to execute `nimble test`. This command runs all tests defined in your project, typically located under the `tests/` directory and utilizing Nim's `std/unittest` module. If `nimble test` reports failures, Atlas analyzes the output to understand the nature of the regression. It then uses its `edit` tool to modify the relevant Nim source files or test cases, ensuring that the upgraded dependency does not introduce new bugs. This cycle of `edit` and `nimble test` repeats until all tests pass. Finally, to maintain code quality and consistency, Atlas automatically formats any touched Nim modules using `nph`, Nim's official formatter, ensuring that all changes adhere to the project's style guidelines before a commit is proposed.

Atlas safety and review for Nim code changes

Atlas prioritizes safety and transparency in Nim code modifications, presenting a unified diff for every file edit and requiring explicit approval before writing. This robust review process, which includes permission-gated tool calls and the ability to snapshot changes as Git patches, ensures that developers retain full control over all 100% of the changes made to their Nim codebase, from `src/` files to `.nimble` configurations.

Atlas is built with multiple layers of safety and review for Nim developers. Before any tool call, such as `bash` or `edit`, is executed, it is permission-gated against allow, ask, and deny rules, giving you granular control. Atlas drafts a plan in a read-only plan agent and asks for your approval before switching to a build agent that can make changes. Crucially, for every file edit, Atlas computes a unified diff and surfaces it for your approval. This means you see exactly what changes Atlas proposes to your Nim source files (e.g., `src/my_library.nim`), test files (e.g., `tests/my_test.nim`), or even configuration files (e.g., `.nimble`). Atlas also snapshots file changes as Git patches, allowing edits to be easily diffed, rolled back, or reviewed in detail. Furthermore, Atlas reads Git branches, status, and diffs, and can stage and create commits on your behalf, always with your explicit approval, ensuring a transparent and controlled workflow for upgrading Nim dependencies.

Step by step

01Run `atlas` in your Nim project directory containing a `.nimble` file.
02Instruct Atlas to upgrade the desired Nim dependency by using `bash` to execute `nimble update <package_name>` or `nimble update --all`.
03If necessary, ask Atlas to use `webfetch` to retrieve the release notes or changelog for the upgraded Nim library to understand breaking changes.
04Have Atlas run `nimble build` via `bash` to compile your Nim project and identify all compiler errors caused by the dependency upgrade.
05For each reported error, instruct Atlas to use the `edit` tool to fix the code, leveraging `lsp`'s `goToDefinition` to inspect new Nim signatures in the upgraded package.
06After fixing compile errors, have Atlas run `nimble test` through `bash` to execute your Nim unit tests (e.g., those using `std/unittest`) and identify any runtime regressions.
07Iteratively use `edit` and re-run `nimble build` and `nimble test` until all compilation errors are resolved and all tests pass.
08Ask Atlas to format all touched Nim modules with `nph` to ensure code style consistency.
09Review the complete unified diff of all changes proposed by Atlas and approve them before Atlas stages and commits the changes to your Git repository.

Frequently asked questions

How does Atlas handle Nim package updates?: Atlas manages Nim package updates by directly invoking `nimble update` or `nimble update --all` through its `bash` tool. It captures the full output of these commands, ensuring that all information regarding the update process, including any warnings or initial errors, is available for analysis and subsequent fixing.
Can Atlas fix compile-time macros in Nim after an upgrade?: Yes, Atlas can address issues related to compile-time macros in Nim. By analyzing the Nim compiler's error output from `nimble build`, Atlas identifies problems within macro expansions or their usage. It then uses its `edit` tool to modify the macro definitions or their call sites, ensuring they are compatible with the upgraded dependency's API.
How does Atlas ensure Nim code style after fixes?: Atlas ensures Nim code style consistency by automatically running `nph`, Nim's official formatter, on any modules it has modified. This step is typically performed after all compilation and test failures have been resolved, guaranteeing that the codebase adheres to established formatting standards before changes are committed.
What safety features does Atlas offer for Nim code changes?: Atlas provides several safety features for Nim code changes, including permission-gated tool calls, a read-only plan agent for drafting changes, and presenting a unified diff for every proposed edit. All changes require explicit developer approval before being written to disk or committed to Git, giving you full control over your Nim project.
Does Atlas integrate with Nim's `std/unittest` module?: Yes, Atlas fully integrates with Nim's `std/unittest` module. It uses `nimble test` via `bash` to execute your project's unit tests. If tests fail, Atlas analyzes the output to identify regressions and uses its `edit` tool to fix the relevant Nim source or test files until all tests pass, ensuring the integrity of your codebase.
Can Atlas read my Nim project's `.nimble` file?: Yes, Atlas is designed to read your Nim project's `.nimble` file. It understands the package structure, required dependencies, and other configurations defined within it. This allows Atlas to accurately manage dependencies and understand the context of your Nim project when performing upgrades and fixes.
How does Atlas know what changed in an upgraded Nim library?: Atlas can use its `webfetch` tool to retrieve the release notes or changelog of an upgraded Nim library directly from the web. This provides Atlas with concrete information about breaking changes, new features, and deprecations, allowing it to make informed decisions when fixing compile and test failures in your Nim codebase.

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